textproduct: Albany

WHAT HAS CHANGED

Red Flag Warning issued for much of the Mid Hudson Valley and Capital District tomorrow where southwest wind gusts up to 35-40 mph combined with RH values around 30% will lead to critical fire weather conditions. SPSs to highlight near critical fire weather conditions will also be issued this evening for the Catskills and western CT/MA once the current SPSs expire at 7 PM. Accordingly, continued trend of lowering dew points and increasing wind gusts tomorrow. Marginal risk for severe thunderstorms remain for areas north and west of the Capital District tomorrow. Finally, Thursday forecast continues to trend drier.

KEY MESSAGES

1) There is an elevated risk for fire spread this afternoon, mainly from the Capital District south and east. These same areas will once again see conditions favorable for rapid fire spread tomorrow.

2) There is a marginal risk for severe thunderstorms tomorrow, mainly for areas north and west of the Capital District.

3) Unsettled weather with periods of rain expected Wednesday into Wednesday night, with a trend towards drier but cool weather for the end of the week into next weekend.

DISCUSSION

KEY MESSAGE 1...As of 2:35 PM EDT...Temperatures have warmed into the upper 60s to around 70 this afternoon for valley areas despite having a few more clouds around earlier in the day than previously expected. With deep mixing ongoing, dew points remain in the mid 30s for many areas east and south of of the Capital District, resulting in RH values of 30-35%. Winds are also quite breezy from the southwest gusts up to 25-30 mph per latest NYS Mesonet and ASOS obs. RH values should begin to rise with diminishing wind gusts towards sunset. RH values tonight recover to 60-80%, highest in the ADKs. SPSs remain in effect through this evening for the Capital District south and east as the combination of drying fine fuels, gusty winds, and low RH will lead to an elevated risk for fire spread.

Tomorrow will once again feature enhanced fire weather conditions, mainly for the same areas as today. It will be about 10 degrees F warmer than today, but dew points will also be a little higher as well. Nevertheless, with deep mixing expected once again and some mid-level dry air in place, we lowered RH values from the NBM to as low as 27-33% in the Capital District and Mid Hudson Valley. Lowest RH values will be in the immediate Hudson Valley where there there will be downsloping off of the Catskills, which should also help push temps into the low 80s. RH also looks to drop into the 35-40% range for the Catskills and southwestern New England. Winds also will be stronger than today, with gusts potentially as high as 30-40 mph, easily surpassing the 25 mph Red Flag threshold. We coordinated with state partners, who confirmed that despite vegetation continuing to green up, there are still enough areas with exposed fine fuels that are dry enough to support an increased risk for fire spread. Given these conditions, a Red Flag Warning was issued for tomorrow for portions of the Hudson Valley FDRA down to Ulster and Dutchess Counties where RH should be lowest. For the Catskills and southwestern New England, where RH is expected to fall short of critical thresholds, another SPS will be issued once the current one expires this evening. For areas further north and west, higher RH values and afternoon showers/thunderstorms should prevent the need for any SPSs.

KEY MESSAGE 2...A cold front associated with an occluded sfc low centered near Hudson Bay will approach from the west tomorrow, with a pre-frontal trough out ahead of the main cold front. For our area, in the warm sector, the combination of temperatures in the 70s to low 80s and increasing dew points, especially north and west of the Capital District, will lead to up SBCAPE values increasing up to around 5001000 J/kg. ~40 kt southwest LLJ and 50+ kt southwesterlies at 500 mb will lead to deep-layer shear values of around 40kt, with much of this in the 0-3 km layer.

Main question is whether or not forcing with the pre-frontal trough (or any mesoscale lake breeze boundaries) will be strong enough for convective initiation (CI) to occur, especially given that upper- level support does not look impressive with a lack of height falls aloft and the main cold front remaining to our west through the day tomorrow. The presence of some mid-level dry air may also make it tough for convection to get going. However, if any storms occur, then discrete cells would initially be possible with deep-layer shear vectors oriented with a somewhat perpendicular component to the approaching boundary. Main hazard would be damaging wind gusts, especially due to a deeply mixed BL resulting in 800-1000 J/KG of DCAPE per latest CAM guidance. Tornado threat looks low due to how high LCLs are despite some low-level veering of the winds and curvature to hodographs. A few instances of marginally severe hail can't be totally ruled out either due to WBZ heights below 9 kft, modestly steep mid-level lapse rates, and mid-level dry air allowing for evaporative cooling. SPC has kept this area in a marginal risk for severe weather, which seems appropriate given favorable kinematics but marginal thermodynamic environment and lack of better forcing.

The other point of forecast uncertainty is how far south and east convection could potentially reach tomorrow afternoon and evening should storms develop. It does not appear at this time that convection would make it south/east of the Capital District, with the highest chance for a strong to severe storm mainly in the southern ADKs and upper Hudson Valley. We have trimmed back the southeastward extent of PoPs from the NBM to be more in line with this thinking, which is supported by most CAM guidance. Any threat for severe weather should diminish after sunset with the loss of daytime heating.

KEY MESSAGE 3... Better chance for showers and perhaps an embedded thunderstorm looks to be Tuesday night into Wednesday as the cold front tracks into our region. A wave of low pressure will develop along the front Wednesday as southern stream shortwave energy aloft tracks along the low-level thermal gradient. This should result in widespread rain through the day Wednesday, bringing a much-needed soaking rain to the region. Another southern stream upper shortwave will track along the front Thursday, but current guidance suggests that the overall positive tilt of the upper trough axis will keep this second resulting sfc low south and east of our region. Therefore, the Thursday portion of the forecast has trended drier compared to previous forecasts. Model forecast soundings are now showing much in the way of elevated instability, so this looks to mainly be a stratiform rain. Latest NBM guidance continues to suggest a 35-50% chance for >1" of rain from Tuesday through Thursday morning north and west of the Capital District, less than a 30% chance for areas south and east. These rainfall amounts will likely lead to some within-bank river rises, but are not expected to lead to any flooding issues. Additionally, given lack of instability, rainfall rates are not expected to be high enough to result in any short fuse (flash flooding) hydro issues.

Behind the cold front, drier conditions are expected Thursday into the weekend, although there could still be isolated showers at times with several shortwave disturbances pinwheeling around an upper low that will be centered near Hudson Bay. Best chance may be Saturday, where guidance is suggesting a slightly more amplified upper shortwave disturbance tracking overhead. temperatures remain below normal for the end of the week into next weekend, with highs mainly in the 50s (terrain) to low 60s (valleys) and overnight lows in the 40s.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Through 18Z Tuesday...VFR conditions are expected to prevail across all terminals over the next 24 hours, with some SCT-BKN mid-level clouds at all sites except for KPOU, which is seeing mostly clear skies to start off the period. These clouds will start to diminish by this evening, leaving mostly SCT high-level clouds at all terminals. Mid-level moisture is expected to return early Tuesday morning and bring cigs back down into the 6000-10000 ft range. There is a slight chance for scattered rain showers at KALB and KPSF, but no significant impacts on vis or cigs is expected.

Southwesterly winds are remaining moderate and gusty at all terminals this afternoon, with gusts up to 20-25 kts expected to continue into this evening. Winds will begin to decouple around 00Z tonight, dropping to just below 10kts at all terminals with a few lingering gusts up to 15 kts at KALB and KPOU. LLWS will begin to develop after 04Z with 2 kft winds increasing up to 40 kts out of the southwest while surface winds remain light out of the south. This will persist until mid-morning on Tuesday, when diurnal heating allows for better mixing. As a result, gusty winds out of the south-southwest will return by 14Z, with gusts reaching back up to 25-30 kts.

Outlook...

Tuesday Night: Moderate Operational Impact. Breezy. Chance of SHRA...TSRA. Wednesday: High Operational Impact. Definite RA. Wednesday Night: High Operational Impact. Likely SHRA. Thursday: Low Operational Impact. Slight Chance of SHRA. Thursday Night: Low Operational Impact. NO SIG WX. Friday: Low Operational Impact. Breezy. NO SIG WX. Friday Night: Low Operational Impact. NO SIG WX. Saturday: Moderate Operational Impact. Chance of SHRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Red Flag Warning from noon to 7 PM EDT Tuesday for NYZ208. MA...None. VT...None.